Coating composition

Abstract

An acidic aqueous solution for coating metallic substrates and consisting essentially of hexavalent chromium, reduced chromium, an alkylphenoxypoly(alkyleneoxy)ether and dispersed acrylic resin solids.

I claim: 
     
       1. In a coating composition of the type which is effective in forming on a metallic surface a corrosion-resistant coating and which comprises an acidic aqueous coating solution containing hexavalent chromium, reduced chromium and dispersed acrylic resin solids, and of the type which, when applied to a substrate by an applicator roll, tends to deposit on the roll excessive amounts of chromium, the improvement comprising inclusion in the composition of an alkylphenoxypoly(alkyleneoxy)ether surfactant in an amount sufficient to deter said excessive chromium build-up. 
     
     
       2. A composition according to claim 1 wherein the surfactant is nonylphenolpolyglycol benzyl ether. 
     
     
       3. A composition according to claim 1 or 2 including at least about 0.03 g/l of said surfactant. 
     
     
       4. A composition according to claim 1 or 2 including about 0.4 to about 7 g/l of said surfactant. 
     
     
       5. A composition for coating metal surfaces to enhance the corrosion resistance and paint adhesion properties thereof and comprising an acidic aqueous solution consisting essentially of at least about 1 g/l of hexavalent and formaldehyde-reduced chromium, about 40 to about 60 wt. percent of the chromium being in reduced form, at least about 0.06 g/l of phosphoric acid, at least about 0.03 g/l of alkylphenoxypoly(alkyleneoxy)ether surfactant and dispersed therein at least about 0.5 g/l of acrylic resin solids. 
     
     
       6. A composition according to claim 5 including about 10 to 50 g/l of hexavalent and formaldehyde-reduced chromium, about 0.06 to about 10 g/l of phosphoric acid, about 5 to about 25 g/l of acrylic resin solids and about 0.4 to about 7 g/l of surfactant. 
     
     
       7. A composition according to claim 6 including Triton CF-54 surfactant and Rhoplex AC-73 latex. 
     
     
       8. In a coating process in which a composition for coating a metallic surface is contacted with a roll, the coating composition being of the type which forms on the metallic surface a corrosion-resistant coating and comprising an acidic aqueous solution containing hexavalent chromium, reduced chromium and dispersed acrylic resin solids and having a predetermined surface tension below that of water, and also of the type which tends to deposit on the roll chromium in excessive amounts which tend to affect adversely the coating process, the improvement comprising using in the process said composition modified by having therein alkyl phenoxypoly(alkyleneoxy)ether surfactant in an amount which is sufficient to deter the deposit on the roll of said excessive chromium and which imparts to the composition a surface tension below said predetermined surface tension. 
     
     
       9. An aqueous concentrate such that an aqueous composition containing about 10 to about 20 wt.% of the concentrate consists essentially of the coating composition of claim 4. 
     
     
       10. An aqueous concentrate such that an aqueous composition containing about 10 to about 20 wt.% of the concentrate consists essentially of the coating composition of claim 1, 2, 5, 6 or 7. 
     
     
       11. A composition according to claim 1 wherein said alkylphenoxypoly(alkyleneoxy)ether is an alkylphenoxypoly(ethyleneoxy)ether. 
     
     
       12. A composition according to claim 11 including at least about 0.03 g/l of said surfactant. 
     
     
       13. A composition according to claim 11 including at least about 0.4 to about 7 g/l of said surfactant. 
     
     
       14. A process according to claim 8 wherein the surfactant is nonylphenolpolyglycol benzyl ether. 
     
     
       15. A process according to claim 8 or 14 wherein said composition includes at least about 0.03 g/l of said surfactant. 
     
     
       16. A process according to claim 8 or 14 wherein said composition includes about 0.4 to about 7 g/l of said surfactant. 
     
     
       17. In a coating composition of the type which is effective in forming on a metallic surface a corrosion-resistant coating and which comprises an acidic aqueous coating solution containing hexavalent chromium, reduced chromium and dispersed acrylic resin solids, and of the type which, when applied to a substrate by an applicator roll, tends to deposit on the roll excessive amounts of chromium, the improvement comprising inclusion in the composition of Triton CF-54 surfactant in an amount sufficient to deter said excessive chromium build-up. 
     
     
       18. A composition according to claim 17 including at least about 0.03 g/l of said surfactant. 
     
     
       19. A composition according to claim 17 including about 0.4 to about 7 g/l of said surfactant. 
     
     
       20. A composition for coating metal surfaces to enhance the corrosion resistance and paint adhesion properties thereof and comprising an acidic aqueous solution consisting essentially of at least about 1 g/l of hexavalent and formaldehyde-reduced chromium, about 40 to about 60 wt. percent of the chromium being in reduced form, at least about 0.06 g/l of phosphoric acid, at least about 0.03 g/l of Triton CF-54 surfactant and dispersed therein at least about 0.5 g/l of acrylic resin solids. 
     
     
       21. A composition according to claim 20 including about 10 to 50 g/l of hexavalent and formaldehyde-reduced chromium, about 0.06 to about 10 g/l of phosphoric acid, about 5 to about 25 g/l of acrylic resin solids and about 0.4 to about 7 g/l of surfactant. 
     
     
       22. A process for forming a coating on a metallic surface comprising contacting the surface with the coating composition of claim 1, 2, 5, 6, 7, 11, 12, 13, 17, 18, 19, 20 or 21. 
     
     
       23. A process according to claim 22 including applying said coating composition to said metallic surface with an applicator roll.